Tuesday, January 15, 2013

What's going on in the Arctic? The winter sea ice freeze is on, but Arctic sea ice cover still 1 million km2 below historical averages

It's been quite a while since I gave you an update on what's happening in the Arctic.

First of all, the Arctic Oscillation shifted recently from its Positive Phase to its Negative Phase; it has been mostly in the Positive Phase since the 1970s . During the Positive Phase there is a large low pressure region dominating the Arctic, but during the Negative Phase there is a large high pressure system there. This switch means that masses of cold Arctic air are more likely to push south and perhaps stay longer than they used to. This is especially true for western North American. This also helps explain the ice-box conditions we have been experiencing lately in the mountain west.

In other news, the Arctic Ocean sea ice freeze is well under way. After the record ice melt of the summer of 2013, climatologists are keeping an interested eye on 2013's freeze up. As the map below from the NSIDC.org shows, sea ice extent is at or sightly above normal in the Bering Sea and beyond the Kamchat peninsula. At the same time, it is well below historical averages east of Scandinavia and south of Greenland.

If you recall, the Bering Sea produced above average sea ice coverage last year, and the lower than average sea ice in east of Greenland also lagged behind historical averages.

Though sea ice production and sea ice extent are still rising - as is to be expected this time of year - current sea ice extent is about 1 million km2 below historic averages (see the graph below from the NSIDC.org)

FYI - The last time sea ice cover reached or exceeded the historic average for this time of year was in 1998 - yep, 15 years ago. Every year since then, mid-January sea ice extent has been below average. The take home message is that the Arctic continues to warm, and that sea ice extent continues to decline (on average) as the years go by.